1. Field of the Invention:
This invention relates to the packaging art and has particular reference to an improved wrapper for protectively sleeving electric lamp bulbs and to the lamp package which is thereby produced.
2. Description of the Prior Art:
Electric lamp bulbs of the incandescent type employed in the home are presently packaged for shipment by inserting them into open-ended tubular sleeves or wrappers of single-face corrugated paperboard and placing the resulting lamp packages or so-called lamp "packs" into a cardboard box. To facilitate the handling of the sealed boxes in the warehouse and during loading and unloading, a number of them are usually placed on a pallet and the pallets are then stacked one upon the other. As a result of such stacking, the individual lamp wrappers of the lamp packages within the shipping boxes are subjected to compressive stresses which frequently cause the wrapper walls to buckle and collapse -- with the result that the glass bulbs are sometimes crushed and broken.
Such compressive stresses are also produced when the loaded shipping box is being sealed in the factory and the outer flaps of the box are pressed firmly against the inner flaps to glue or staple them together.
Lamp wrappers made from single-face corrugated paperboard are well known in the art and are dimensioned to enclose and snugly grip either a single lamp bulb or a pair of bulbs to provide a single-lamp package or a dual-lamp package, respectively. In the case of wrappers designed for a pair of bulbs, an integral partition wall is provided within the wrapper to prevent the packaged lamps from physically contacting one another. Regardless of the type of wrapper involved, standard practice in the art is to fabricate the wrappers in such a way that the corrugations extend perpendicular to the longitudinal axis of the wrapper and, hence, to the direction in which the lamps are inserted into the wrappers. Conventional open-ended lamp wrappers thus employ corrugations or flutes that are parallel to the transverse axis of the wrapper.
While wrappers of such construction are satifactory from the standpoint of preventing the packaged lamps from contacting one another and breaking during shipment, they frequently fail to protect the lamps under compressive stress conditions encountered when the shipping containers are being sealed in the lamp factory or when the palletized containers are stacked in the warehouse or are being shipped. This deficiency arises from the fact that while corrugated packaging material has excellent compressive strength in the direction along which the corrugations extend, it buckles when subjected to stresses in a direction perpendicular to the corrugations (in the same plane). The latter condition is frequently encountered during the handling and shipment of palletized loads of lamp packs and sometimes causes the packaged lamps inside the shipping container to be broken.